Multimode optical fibers are capable of conveying modulated monochromatic light beams of different wavelengths, especially in the ranges of 0.86 to 0.9.mu. and 1.06 to 1.3.mu. for which the attenuation of such optical fibers is at a minimum.
Conventional systems of this type utilize prisms or equivalent dispersion means at a transmitting station for refractively combining the several constituent beams into a single composite beam and at a receiving station for redistributing the several constituent beams to their respective destinations. Even with glasses or other transparent materials of large dispersion ratio, the relatively narrow spread of available wavelengths limits the number of monochromatic beams that can be conveniently separated and channeled to respective loads such as photodetectors for demodulation. Other optical means heretofore used for the mixing of individual beams, such as semitransparent beam splitters, have the disadvantage of large transmission losses.